Question

1. If a + b = 6 and ab = 8, then the
value of (a - b) is
O +4
O +3
O +2
O None of these

Answer 1

Answer:

since, (a+b)² = a² + b² + 2ab

=> 6² = a² + b² + 2×8

=> 36 = a² + b² + 16

=> 36 - 16 = a² + b²

=> a² + b² = 20

Since, (a-b)² = a² + b² - 2ab

=> (a-b)² = 20 - 2×8

=> (a-b)² = 20 - 16

=> (a-b)² = 4

=> √(a-b)² = √4

=> a-b = 2

So, option (3)= +2, is correct.